... use as a greasecavity.Double and treble sheave purchase blocks are of a similar construction tothe single sheave, except that a partition plate separates the sheaves. Theyare used extensively ... RIGGINGSTEEL WIRE ROPEA steel wire rope is composed of three parts – wires, strands and theheart. The heart is made of natural fibre, though recently synthetic fibrehas been used when resistance ... The stopper should be examined for wear and tearbefore use, and if there is any sign of deterioration, the stopper should berenewed. The mariner should ensure that the stopper is secured, thenpass...